Method for the determination of 313 Residual Pesticides in Black tea using LCMS-8045 and GCMS-TQ8040 NX

Significance of the Topic

A robust, high-throughput multi-residue analytical approach is crucial to ensure tea safety and compliance with global Maximum Residue Limits (MRLs). Black tea poses particular challenges due to its complex matrix and the diverse chemical properties of over 300 registered pesticides. Implementing rapid, sensitive quantification methods supports regulatory monitoring, quality assurance in tea production, and protection of consumer health.

Objectives and Study Overview

This study aimed to develop and validate a streamlined procedure for simultaneous determination of 313 pesticide residues in black tea. Utilizing Shimadzu’s ultra-fast LC-MS/MS (LCMS-8045 with Nexera X2) and GC-MS/MS (GCMS-TQ8040 NX) systems, the work targeted 203 analytes by LC-MS/MS and 131 by GC-MS/MS, with 21 overlapping compounds. Key performance metrics—sensitivity, precision, accuracy, and throughput—were evaluated against SANTE guidelines.

Methodology and Instrumentation

Sample Preparation:

• Modified QuEChERS extraction with acidified acetonitrile (LC) or ethyl acetate (GC), salt partitioning, and cleanup using PSA, C-18, GCB (plus CaCl₂ for GC).
• Evaporation and reconstitution in ethyl acetate; final dilution to achieve matrix-matched calibration.

Chromatographic Conditions:

• LC: Shim-pack XR-ODS II column, 150×3.0 mm, rapid gradient (21 min runtime), flow 0.4 mL/min, 10 µL injection.
• GC: SH-I-5Sil MS column, 30 m×0.25 mm, 25 min oven program, splitless injection of 1 µL.

Mass Spectrometry:

• LC-MS/MS: Electrospray ionization at 300 °C, one target and two reference MRM transitions.
• GC-MS/MS: Electron ionization at 230 °C, optimized MRM transitions from Shimadzu Smart Pesticides Database.

Instrumentation

• Shimadzu LCMS-8045 coupled with Nexera X2 (SIL-30AC autosampler).
• Shimadzu GCMS-TQ8040 NX with AOC-20i+s autosampler.
• Data processing via LabSolutions Insight software and Shimadzu method packages.

Key Results and Discussion

System Performance:

• Linearity: R² > 0.99 for all calibration curves (LC 1–50 µg/L; GC 1–15 µg/L or doubled for shared standards).
• Precision: Repeatability (RSDr) and reproducibility (RSDR) < 20% at LOQ for all compounds.
• Specificity: Blank matrices showed < 30% of reporting level response.

Recovery and Sensitivity:

• Mean recoveries of 70–120% at LOQ for 169 LC-MS/MS and 119 GC-MS/MS analytes; remaining compounds still met precision criteria.
• LOQs achieved: 10 µg/kg for 198 LC-MS/MS and 81 GC-MS/MS compounds; additional analytes with LOQs of 20–40 µg/kg.

Run Time and Throughput:

• Short analysis cycles (21 min LC, 25 min GC) maximize sample throughput.
• Lower injection volumes and flow rates extend column life and reduce solvent usage.

Benefits and Practical Applications

• Comprehensive coverage of major regulatory lists (EU, FSSAI, APEDA, Japan).
• High sensitivity and reproducibility support routine monitoring in QA/QC labs.
• Adaptability for other complex food matrices with minimal method adjustments.
• Enhanced throughput aligns with industrial and regulatory demand for rapid testing.

Future Trends and Opportunities

• Integration with high-resolution mass spectrometry for non-targeted screening and unknown pesticide detection.
• Automation of sample preparation workflows to reduce manual handling and variability.
• Miniaturization and green chemistry approaches to lower solvent consumption further.
• Cloud-based data management and AI-driven interpretation to accelerate decision making.

Conclusion

The validated multi-residue method combining modified QuEChERS extraction with Shimadzu’s LC-MS/MS and GC-MS/MS platforms delivers rapid, sensitive, and reliable quantification of over 300 pesticide residues in black tea. The approach meets stringent regulatory criteria, offers high throughput for routine monitoring, and provides a foundation for future expansion to broader food safety applications.

References

1. Anastassiades M., Lehotay S.J., Štajnbaher D., Schenck F.J. Fast and Easy Multiresidue Method Employing Acetonitrile Extraction/Partitioning and “Dispersive Solid-Phase Extraction” for the Determination of Pesticide Residues in Produce. J. AOAC Int. 86, 412–431 (2003).
2. European Commission SANTE/12682/2019. Guidance Document on Analytical Quality Control and Method Validation Procedures for Pesticide Residues Analysis in Food and Feed.